Disk array devices, when configured to constitute RAID (Redundant Array of Independent (or Inexpensive) Disks), enable parallel operation of multiple disks and thus realize data reading and data writing requested by a host at high speed. In such disk array devices, redundant data corresponding to an RAID level such as Mirror or Parity is created in order to provide high fault tolerance to protect against disk failure.
Further, in the disk array devices, a verification code for detecting data corruption and errors in a destination address that could occur during transfer is appended to received data for the purpose of improving the reliability of the whole system. For example, in data writing, data received from a host is divided into logical data blocks each having a constant data length, and a verification code is appended to each logical data block, so that the logical data having the verification code appended thereto is stored in a cache memory or a disk. After that, when data reading is requested by the host, a verification code of the relevant data is checked before the data is transferred to the host, whereby it is ensured that the data to be transferred to the host is identical to the data that has been written.
As a specific example of such verification codes, a technique of appending an LRC (Longitudinal Redundancy Check) code for detecting data bit errors that could occur during transfer and also appending an LA (Logical Address) for detecting address errors is typically known (see Patent Literature 1). In recent years, a DIF (Data Integrity Field) proposed by T10, which is a storage interfaces technical committee, has been spreading as a standard format of a verification code.
There are also cases in which an interface device that supports the process of creating/appending and checking/deleting such a verification code is used as a host adapter of a disk array device. In such cases, in data writing, a disk adapter, which is an entrance of a disk array device, appends a verification code to data received from a host. Meanwhile, in data reading, the disk adapter checks for the integrity of the verification code. Accordingly, it is possible to ensure that a data error or data loss has not occurred in the device.